Queries generated incorrectly in class methods about rails HOT 2 CLOSED

One of the differences between the first and second assertions is that the second assertion chains the parents method to the Category.where(id: category.id) query. In other words, it calls the parents method on the result of the Category.where(id: category.id) query. Since the parent record is not included in the result of the Category.where(id: category.id) query, calling the parents method on this result will not return the parent record.

To prove this, you can call Category.parents.pluck(:id), which should pass the test. In this case, all Category records will be available for the parent chain method.

assert_equal([parent.id], Category.parents.pluck(:id))

Trivial: Instead of using a class method, you can use a scope for the same purpose.

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Hi @danielwaterworth , thanks for the report. The two queries are not the same. If you were to expand the self.parents method on the base scope in the second query, it would look something like this:

Category.where(id: category.id).parents.pluck(:id) #expands to

Category.where(id: category.id).where(id: Category.where(id: category.id).select(:parent_category_id)).pluck(:id))

Your base base scope still will have .where(id: category.id) on it.

The first one is this:

Category.where(id: Category.where(id: category.id).select(:parent_category_id)).pluck(:id))

hence the difference.

Let me know if you still some issue with this. Thanks!

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